linux-kernel - Re: [PATCH v3] drm/v3d/v3d_drv: Fix PM disable depth imbalance

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Date:   Wed, 1 Jun 2022 21:55:02 +0800
From:   Miaoqian Lin <linmq006@...il.com>
To:     Emma Anholt <emma@...olt.net>, David Airlie <airlied@...ux.ie>,
        Eric Anholt <eric@...olt.net>, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     Miaoqian Lin <linmq006@...il.com>
Subject: Re: [PATCH v3] drm/v3d/v3d_drv: Fix PM disable depth imbalance

Hi, Daniel

On 2022/6/1 21:26, Daniel Vetter wrote:
> On Wed, Jun 01, 2022 at 04:20:50PM +0400, Miaoqian Lin wrote:
>> The pm_runtime_enable will increase power disable depth.
>> If the probe fails, we should use pm_runtime_disable() to balance
>> pm_runtime_enable().
>> Also call disable function in remove function.
>>
>> Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")
>> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
>> ---
>> Changes in v3:
>> - call pm_runtime_disable() in v3d_platform_drm_remove
>> - update commit message
>>
>> Changes in v2
>> - put pm_runtime_disable before dma_free_wc
>> - rename dma_free to pm_disable
>>
>> v1: https://lore.kernel.org/r/20220105120442.14418-1-linmq006@gmail.com
>> v2: https://lore.kernel.org/r/20220106124657.32737-1-linmq006@gmail.com
> Maybe a bit late since we're at v3 already, but are there no devm_
> functions here that would dtrt automatically? 

Sorry I don't see one, or we can use devm_add_action_or_reset() to add handling

action. something like disp_cc_sm8250_probe() in drivers/clk/qcom/dispcc-sm8250.c

How do you think?

> Or is there another reason
> we can't use them?
> -Daniel
>> ---
>>  drivers/gpu/drm/v3d/v3d_drv.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/v3d/v3d_drv.c b/drivers/gpu/drm/v3d/v3d_drv.c
>> index 1afcd54fbbd5..f3380399fe17 100644
>> --- a/drivers/gpu/drm/v3d/v3d_drv.c
>> +++ b/drivers/gpu/drm/v3d/v3d_drv.c
>> @@ -286,7 +286,7 @@ static int v3d_platform_drm_probe(struct platform_device *pdev)
>>  
>>  	ret = v3d_gem_init(drm);
>>  	if (ret)
>> -		goto dma_free;
>> +		goto pm_disable;
>>  
>>  	ret = v3d_irq_init(v3d);
>>  	if (ret)
>> @@ -302,7 +302,8 @@ static int v3d_platform_drm_probe(struct platform_device *pdev)
>>  	v3d_irq_disable(v3d);
>>  gem_destroy:
>>  	v3d_gem_destroy(drm);
>> -dma_free:
>> +pm_disable:
>> +	pm_runtime_disable(dev);
>>  	dma_free_wc(dev, 4096, v3d->mmu_scratch, v3d->mmu_scratch_paddr);
>>  	return ret;
>>  }
>> @@ -316,6 +317,7 @@ static int v3d_platform_drm_remove(struct platform_device *pdev)
>>  
>>  	v3d_gem_destroy(drm);
>>  
>> +	pm_runtime_disable(&pdev->dev);
>>  	dma_free_wc(v3d->drm.dev, 4096, v3d->mmu_scratch,
>>  		    v3d->mmu_scratch_paddr);
>>  
>> -- 
>> 2.25.1
>>